After 2 days of disassembly and cleaning with thinner I can't solve the problem. All of a sudden the airbrush started pulsating as if the air source was getting interrupted. The airbrush is hooked up to a Campbell-Hausfeld compressor with tank + Testors moisture trap.
There's no pulsating/sputtering when shooting pure thinner, only when shooting paint!
I had to switch to plan B which is my old Aztek.
The model is done with the exception of the canopy which I masked and started spraying. Even then the SOB launched this last attack on me in the very last step. Because of the sputtering the finish of the canopy frames could end up a little rough.
Those models are mean SOBs, they launch those attacks on me on purpose.